The present invention relates to blinds for regulating the light and, more specifically, to a transmission system for a motor-driven blind, which is operated to move vertical slats toward the center area or two sides between the extended position and the extended position.
In order to eliminate the drawback of manual operation, various blinds with motor-driven transmission system have been disclosed. FIGS. 1 and 2 illustrate a blind with a motor-driven transmission mechanism according to the prior art. As illustrated, the blind 10 comprises a first power drive 12 and a second power drive 23 reversely disposed at two ends of the top track 11. The first power drive 12 comprises a motor 13, a belt transmission mechanism 14, an axle 15 coupled to the motor 13 through the belt transmission mechanism 14, a transmission gear train 16, a transmission shaft 17 coupled to the belt transmission mechanism 14 through the transmission gear train 16, a worm 19 supported in carriers 18 and coupled to the transmission shaft 17, and a worm gear 20 meshed with the worm 19 and driven by the worm 19 to rotate respective hooks 21 and the vertical slats 22 at the hooks 21 forwards/backwards within a limited angle. The second power drive 23 comprises a motor 24, a belt transmission mechanism 25, an axle 26 coupled to the motor 24 through the belt transmission mechanism 25, a transmission gear train 27, and a lead screw 28 inserted through the carriers 18 and threaded into a nut 29 in the first carrier and coupled to the belt transmission mechanism 25 through the transmission gear train 27. Upon rotary motion of the lead screw 28, the first carrier is caused to move along the lead screw 28. The carriers 18 are coupled to one another by link means 30, so that the carriers 18 are moved one after another in one direction to receive or extend out the vertical slats 22 upon rotary motion of the lead screw 28. Therefore, when the motor 24 is turned in one direction, the slats 22 are extended out. On the contrary, when the motor 24 is turned in the reversed direction, the slats 22 are received together. This structure of the blind is functional. However, the slats 22 can only be moved from the left (right) side to the right (left) side to the extended or received position, i.e., the slats 22 cannot be moved from two sides toward the center area to the extended position, or from the center area toward the two sides to the received position. In a big scale blind, moving the slats between the received position and the extended position takes much time and consumes much power supply. Further, because the slats are moved in same direction, the motion of the slats is not symmetrical, i.e., the motion of the slats is not visually harmony.
The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a transmission system for a motor-driven blind, which is operated to move vertical slats toward the center area or two sides between the extended position and the received position. According to one aspect of the present invention, the transmission system is installed in the track of a motor-driven blind and controlled to move vertical slats of the motor-driven blind between a received position and an extended position and to rotate the vertical slats in regulating the light after the vertical slats have been moved to the extended position. According to another aspect of the present invention, the transmission system includes a first power drive controlled to rotate the vertical slats to the desired angle through a transmission shaft and worm and worm gear sets, and a second power drive controlled to move the vertical slats from the ends of the track toward the middle or from the middle of the track toward the ends between the extended position and the received position through two reversed screws.